Tuneable reflex klystron



1969 P. H. M. KORST ETAL ,487,2 7

TUNEABLE REFLEX KLYSTRON Filed April 27. 1967 INVENTOR$ PETER H. M. K'ORST ADRIANUS F.C. VERHOEVEN THOMAS J. WESTERHOF United States Patent US. Cl. 315-5.21 4 Claims ABSTRACT OF THE DISCLOSURE A reflex klystron suitable for operation at frequencies above 37.5 gHz./s. (8 mm.) and up to 200 gHz./s (1.5 mm.) provided with a moveable tuning plate connected with the tube wall by means of a diaphragm, a continuous groove being provided in the surface adjoining the output resonant cavity and displaceable parallel to itself.

The invention relates to a reflex klystron suitable for producing oscillations having frequencies exceeding 37.5 gHz./s. More particularly, the invention relates to a reflex klystron operable at 200 gHz./s. (wavelength 1.5 mm.) provided with an output device having a moveable tuning plate connected with the tube wall by means of a diaphragm, a continuous groove being provided in the urface adjoining the output resonant cavity and displaceable parallel to itself.

In reflex klystrons for longer wavelengths the moveable part of the tuning plate heretofore was connected to the tube wall by means of a corrugated diaphragm joining the moveable part by a groove. At wavelengths below 8 mm. (37.5 gHz./s.) this diaphragm was replaced by a continuous thin part of the tuning plate; however, the shape of the surface facing the output resonant cavity was kept equal to the continuous rib and groove formed by the original corrugated diaphragm. For it was found that the operation of the tube is greatly influenced already by small modifcations of the shape of said surface. With th increase in frequency, the operative part of the tuning plate was therefore proportionally reduced in dimensions.

However, it becomes more diflicult to achieve the shape of the surface according as the dimensions are reduced. Below a wavelength of 2 mm., this shape can hardly be realized any more by the tool means now available and it becomes already very expensive at wavelengths below 4 mm.

Investigations have shown that a construction of mechanically much greater simplicity can be obtained which moreover operates more satisfactorily if, according to the invention, the continuous groove has a V-shaped crosssection and the surface of the moveable part displaceable parallel to itself is otherwise flat. The groove preferably has an apex of 60 and its depth is preferably approximately of the minimum wavelength to be attained, the average diameter of the continuous groove being chosen approximately equal to said wavelength. These dimensions are not critical, however, as compared with the remaining dimensions of the moveable part of the tuning plate. The groove can now be cut by means of a conventional chisel.

The invention will now be described more fully with reference to the drawing, in which the sole figure is a sectional view of part of the output resonant cavity of a reflex klystron according to the invention.

Referring now to the drawing, reference numeral 1 denotes a cathode and reference numeral 2 denotes a beamforming electrode. The electron beam passes through apertures in the anode 3 and tuning plate 4 which enclose a resonant cavity 12 which is coupled to the utput wave-guide 10. The beam then enters a reflector space, whereupon it is reflected by a reflector 7.

Tuning plate 4 is connected by means of a thin-walled portion 8 with an annular part 5 and with the tube wall 9.

Tuning plate 4 is also connected with the reflector housing 6 which can be displaced along the tube axis and thus varies the wavelength of the resonant cavity thereby plastically deforming the thin-walled portion 8. The tuning plate 4 is further connected by means of a thin-walled portion 8 with an annular part 5 and with the tube wall 9.

A continuous groove 11 of a V-shaped cross-section having an apex of 60 is cut in the surface of the tuning plate 4 displaceable parallel to itself. The depth of the groove 11 is about 15% of the minimum wavelength to be tuned and its average diameter is approximately equal to this wavelength.

At a wavelength of 1.5 mm., the average diameter of the groove 11 of FIG. 1 is 1.36 mm. and its depth is 0.19

It has been found that at wavelengths of up to 8 mm. the groove in accordance with the invention is not only simpler, but also has a favorable effect and renders it possible to tune in a wider wavelength range than with known constructions.

Due to the simple shape of the tuning plate 4, reflex klystrons can also be constructed for use at wavelengths down to 1.5 mm.

While the invention has been described in connection with a specific embodiment and applications thereof, other modifications will be apparent to those skilled in this art without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A reflex klystron suitable for producing oscillations having frequencies exceeding 37.5 gHz./s. comprising an evacuated envelope enclosing an electrode beam-forming element, an anode and a reflector, an output device having a moveable tuning plate, a diaphragm connecting said tuning plate with the wall of the envelope, a continuous groove being provided in the surface of the tuning plate adjoining an output resonant cavity and displaceable parallel to itself, said continuous groove having a V-shaped cross-section, said surface displaceable parallel to itself being otherwise flat.

2. A reflex klystron as claimed in claim 1, in which the V-shaped cross-section of the continuous groove has an apex of 60.

3. A reflex klystron as claimed in claim 1, in which the depth of the continuous groove is from 10 to 20% 0f the minimum wavelength to be tuned.

4. A reflex klystron as claimed in claim 1, in which the average diameter of the continuous groove is approximately equal to the minimum wavelength to be tuned.

References Cited UNITED STATES PATENTS 2,523,031 9/1950 Lafferty 315-5.23

HERMAN KARL SAALBACH, Primary Examiner S. CHATMON, JR., Assistant Examiner US. Cl. X.R. 3l5-5.22; 33383 

